<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>背景颜色循环渐变</title>
    <style>
      div {
        margin: 25vh auto;
        width: 80vw;
        height: 50vh;
        background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
        background-size: 400% 400%;
        animation: gradientBG 15s ease infinite;
      }

      @keyframes gradientBG {
        0% {
          background-position: 0% 50%;
        }
        50% {
          background-position: 100% 50%;
        }
        100% {
          background-position: 0% 50%;
        }
      }
    </style>
  </head>
  <body>
    <div></div>
  </body>
</html>
